Add Heka log decoder for OpenStack

In the future the Heka Lua sandboxes will be moved out of Kolla, and
installed in the Heka container using a deb or rpm package.

Partially implements: blueprint heka
Change-Id: I70fd4af920aa2dfb1c8ef9ce8bf6e0c28507ec3e

docker/heka/plugins/decoders/os_openstack_log.lua

+-- Copyright 2015-2016 Mirantis, Inc.
+--
+-- Licensed under the Apache License, Version 2.0 (the "License");
+-- you may not use this file except in compliance with the License.
+-- You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+require "string"
+require "table"
+local l      = require 'lpeg'
+l.locale(l)
+
+local patt = require 'os_patterns'
+local utils = require 'os_utils'
+
+local msg = {
+    Timestamp   = nil,
+    Type        = 'log',
+    Hostname    = nil,
+    Payload     = nil,
+    Pid         = nil,
+    Fields      = nil,
+    Severity    = nil,
+}
+
+-- traceback_lines is a reference to a table used to accumulate lines of
+-- a Traceback. traceback_key represent the key of the Traceback lines
+-- being accumulated in traceback_lines. This is used to know when to
+-- stop accumulating and inject the Heka message.
+local traceback_key = nil
+local traceback_lines = nil
+
+function prepare_message (service, timestamp, pid, severity_label,
+        python_module, programname, payload)
+    msg.Logger = 'openstack.' .. service
+    msg.Timestamp = timestamp
+    msg.Payload = payload
+    msg.Pid = pid
+    msg.Severity = utils.label_to_severity_map[severity_label] or 7
+    msg.Fields = {}
+    msg.Fields.severity_label = severity_label
+    msg.Fields.python_module = python_module
+    msg.Fields.programname = programname
+    msg.Payload = payload
+end
+
+-- OpenStack log messages are of this form:
+-- 2015-11-30 08:38:59.306 3434 INFO oslo_service.periodic_task [-] Blabla...
+--
+-- [-] is the "request" part, it can take multiple forms.
+
+function process_message ()
+
+    -- Logger is of form "<service>_<program>" (e.g. "nova_nova-api",
+    -- "neutron_l3-agent").
+    local logger = read_message("Logger")
+    local service, program = string.match(logger, '([^_]+)_(.+)')
+
+    local log = read_message("Payload")
+    local m
+
+    m = patt.openstack:match(log)
+    if not m then
+        return -1, string.format("Failed to parse %s log: %s", logger, string.sub(log, 1, 64))
+    end
+
+    local key = {
+        Timestamp     = m.Timestamp,
+        Pid           = m.Pid,
+        SeverityLabel = m.SeverityLabel,
+        PythonModule  = m.PythonModule,
+        service       = service,
+        program       = program,
+    }
+
+    if traceback_key ~= nil then
+        -- If traceback_key is not nil then it means we've started accumulated
+        -- lines of a Python traceback. We keep accumulating the traceback
+        -- lines util we get a different log key.
+        if utils.table_equal(traceback_key, key) then
+            table.insert(traceback_lines, m.Message)
+            return 0
+        else
+            prepare_message(traceback_key.service, traceback_key.Timestamp,
+                traceback_key.Pid, traceback_key.SeverityLabel,
+                traceback_key.PythonModule, traceback_key.program,
+                table.concat(traceback_lines, ''))
+            traceback_key = nil
+            traceback_lines = nil
+            -- Ignore safe_inject_message status code here to still get a
+            -- chance to inject the current log message.
+            utils.safe_inject_message(msg)
+        end
+    end
+
+    if patt.traceback:match(m.Message) then
+        -- Python traceback detected, begin accumulating the lines making
+        -- up the traceback.
+        traceback_key = key
+        traceback_lines = {}
+        table.insert(traceback_lines, m.Message)
+        return 0
+    end
+
+    prepare_message(service, m.Timestamp, m.Pid, m.SeverityLabel, m.PythonModule,
+        program, m.Message)
+
+    m = patt.openstack_request_context:match(msg.Payload)
+    if m then
+        msg.Fields.request_id = m.RequestId
+        if m.UserId then
+          msg.Fields.user_id = m.UserId
+        end
+        if m.TenantId then
+          msg.Fields.tenant_id = m.TenantId
+        end
+    end
+
+    m = patt.openstack_http:match(msg.Payload)
+    if m then
+        msg.Fields.http_method = m.http_method
+        msg.Fields.http_status = m.http_status
+        msg.Fields.http_url = m.http_url
+        msg.Fields.http_version = m.http_version
+        msg.Fields.http_response_size = m.http_response_size
+        msg.Fields.http_response_time = m.http_response_time
+        m = patt.ip_address:match(msg.Payload)
+        if m then
+            msg.Fields.http_client_ip_address = m.ip_address
+        end
+    end
+
+    return utils.safe_inject_message(msg)
+end